Abstract: A process is provided for scrubbing sulfur dioxide out of a flue gas by contacting the flue gas with a scrubbing liquid containing diammonium phosphate and ammonium sulfite and in which the total concentration of phosphates is maintained in a balance with the total concentration of sulfites so that the formation and release of plumes of ammonium sulfite are minimized. The sulfur dioxide in the flue gas reacts with the diammonium phosphate to produce monoammonium phosphate and ammonium bisulfite. A portion of the scrubbing liquid is contacted with ammonium ions to convert the monoammonium phosphate into diammonium phosphate and the ammonium bisulfite into ammonium sulfite, and the same portion of scrubbing liquid is contacted with oxygen to convert the ammonium ammonium sulfite into ammonium sulfate. Ammonium sulfate is removed from the process and the oxidized scrubbing liquid is recycled for further contact with flue gas.